Chapter 4Engine Construction

& Principles of Operationpage 63

Gasoline Engines

• A gasoline fueled engine is a mechanism designed to transform the chemical energy of burning fuel into mechanical energy.

• Single cylinder• Multi-cylinder• V-inline-• Rotary• All have similar Fuel systems, Cooling and

lubrication systems.

Simple Engine operation

• Intake– fuel/air

• Compression– compress it

• Power– Spark

• Exhaust– get rid of it

http://auto.howstuffworks.com/engine1.htm

4 Cycles

Gasoline

• HydroCarbon (HC)

• Refined from Petroleum

• Must: – Ignite readily– Burn Cleanly– Resist detonation– Vaporize easily

• w/o impeding flow-

– Be free of dirt

Gasoline• Assign Octane # 87-89-93• Higher # for higher compression• Shelf life• Leaded/Lead Free

– Tetraethyl lead

• Additives– Ethanol– Methanol– ether

Gas MUST Burn Quickly

• Not over 10% Ethanol

• Liquid gas burns cold & Slow

Fuel is Atomized

• Must be in mist/vapor/atomized

• Increase surface area– Droplets – (Spray paint, Air brush, mist)

Explosion must be contained

• Need to contain to perform work

• Tube

• Sliding plug

• Cap

• Inlet\Outlet

• Direct the flame/explosion

Further Improvements

• Limit area of Explosion

• Tube = Cylinder

• Sliding Plug = Piston

• Cap = Head

• Inlet/Outlet = Valves

Basics for an Engine

• Systems of the engine

• Mechanical

• Carburetion

• Ignition

• Cooling

• Lubrication

Cylinder Block

• Frame of engine

• Keeps parts in alignment

• Iron or Aluminum

• Holes “Bored”

• Cooling fins

• Water Jacket

Crankshaft• Major Rotating part

• Changes Reciprocating motion into rotary motion

• Fly Wheel/Snout

• Output

• Counter weights

• Crank pin / connecting rod journal

• Throw

• Key way

Crankcase

• Rigid

• Hold seals

• Hold oil

• Extreme pressure

Piston• Sliding plug

• Expands during operation

• Ring grooves

• Piston pin/wrist pin

• Head constructions

Pistons

Connecting Piston to Crankshaft

• Wrist Pin

• Retaining clips

• Connecting Rod

• Bearings

• Cap

• Retainer

• Bolts

Intake & Exhaust Ports

• Ports (openings)

• Passages

• Capped w/ poppet valves

                               

Poppet Valves

• 4 stroke engines• Door ways• Pop open• Sit in Valve guides

Valve Spring Assembly

• Holds valve in place

• Closes valve

• Valve

• Spring

• Retainer

• Keeper

Valve Lifters/Tappets

• Rides on Camshaft• Taps/Lifts Valves• Some adjustable

Cam Shaft• Controls OPENING of valves• Duration (time)• Reach (distance)• ½ crank speed

www. http://auto.howstuffworks.com/camshaft.htm

Fly Wheel

• smoothes engine operation

• Magnets cast into

• Key way/groove

• Metal fins – cooling

• Clutch